1. Field of the Invention
The present invention relates to a bumper absorber disposed in a bumper system of an automobile.
2. Description of the Related Art
Heretofore, a bumper system, whose purpose is to protect an automobile body and to suppress injuries of an occupant and a collided object at the collision time, is provided at a front side and a rear side of an automobile. In recent years, the bumper system particularly has been designed to protect against bodily injuries, in which the load applied to legs of a pedestrian is reduced, thereby reducing injury values of the pedestrian.
The bumper system is usually constituted by a bumper fascia, a bumper reinforce and a bumper absorber.
The bumper reinforce is fitted to the automobile body to reinforce and protect the automobile body. Generally, the bumper reinforce is required to have a predetermined strength, and is made of metal, and has a hollow cylindrical structure in which partition walls for reinforcing are formed.
The bumper absorber is disposed outside the bumper reinforce, and is deformed or crushed between the collided object such as legs of the pedestrian and the bumper reinforce at the time of crash. Thus, the bumper absorber absorbs impact energy, and in particular, works to reduce the reaction force toward the collided object. In general, the bumper absorber is made of soft resin foam, soft resin particle foam compact, hollow resin compact and the like.
The bumper fascia covers and conceals the bumper reinforce and the bumper absorber from the exterior of the automobile body, and improves the design of the automobile body. Furthermore, the bumper fascia protects this bumper absorber from the external environment and works to prevent the performance of the bumper absorber from deteriorating. In general, the bumper fascia is formed such that synthetic resin and the like are injection-molded.
The bumper reinforce also functions as a mount for the bumper absorber and as a pedestal when the bumper absorber is crushed and absorbs the impact. In general, the bumper absorber is mounted and fixed on the bumper reinforce so that a convex portion protrudingly formed in the bumper absorber fits an aperture provided in the bumper reinforce. However, a method of mounting the bumper absorber is not limited to this form, and a method is also known, in which the bumper absorber is disposed only between the bumper reinforce and the bumper fascia and no particular fixing means is used.
As such a bumper absorber, JP-A-2003-341449 discloses impact absorption member 100 formed by foam-molding a thermoplastic resin and having a structure as shown in FIG. 1. As shown in the figure, this impact absorption member 100 includes base 101 and a plurality of ribs 102. Ribs 102 are formed on at least one surface side of this base 101, and protrude in the same direction as the direction of the action of the impact load acting on impact absorption member 100. In this patent document, it is described that the rapid increase of compression stress can be suppressed by the provision of such ribs 102 even when the compress strain of impact absorption member 100 is large. Further, it is described that ribs 102 are formed such that those widths are gradually reduced in a tapered shape from base 101 side to the end sides of ribs 102, thereby enhancing the impact absorption performance of impact absorption member 100.